Data

Question 1

Two things to remember on frequency polygons

Answer 1

Plot at mid points

Don’t join end points

Question 2

Two things to remember in grouped frequency tables

Answer 2

Use the midpoints when calculating the mean

(Total freq+1)/2 = median

Question 3

6 things to remember when doing cumulative frequency

Answer 3

Cumulative frequency = running total

Plot at upper bound

Graph has to look like an elongated ‘s’

When plotting use a line of best fit

Join to (0,0)

Inter quartile range = upper quartile - lower quartile

Question 4

6 things to remember on box plot questions

Answer 4

For a list of data find the median (halfway) . Then halfway between the median and lowest value is the lower quartile and halfway between the median and the highest value is the upper quartile.

IQR= UQ-LQ

If the question asks (for example) : 75% of students scored higher than _______ , 75% + 25%= 100% so (25% is the lower quartile) we can do the total - the lower quartile to give us the amount 75% of students scored higher than.